The invention concerns an X-ray reflectometry apparatus comprising an X-ray source configured to emit an incident X-ray beam directed onto a sample measuring position and an X-ray detector configured to detect the X-ray beam following reflection from a surface of a selected sample located in that sample measuring position and with a multiple sample holder comprising an essentially horizontal one- or two-dimensional array of sample resting positions into which solid samples can be placed from an upward direction. A drive mechanism moves the sample holder in one or two directions within a horizontal plane beneath the sample measuring position in order to place a selected sample directly below the measuring position.
An X-ray system of prior art comprises an X-ray source and a detector unit. A sample (wafer) is positioned between the detector and the X-ray source and is disposed on an Euler's balance. A knife-edge is positioned above the sample and can be manually lowered towards the surface of the sample using a micrometer screw adjustment mechanism. An indicating caliper is utilized to measure the separation between the knife-edge and the surface of the sample. This apparatus is only suitable for reflectometry measurements in the middle region of the sample, since, in the event that the sample is moved in the x or y directions, the knife edge moves along therewith and causes blockage of the beam emanating from the X-ray source, since that source is stationary (see “D8 Discover” brochure, Bruker AXS GmbH, Karlsruhe, Germany, 2008).
A screening apparatus of prior art utilizes an X-ray source and a detector to examine a selected one of a plurality of samples disposed in a sample holder configured as a plate having 96 receptacles in which 96 samples can be placed. A knife-edge is located above the sample and is intended to prevent other samples from being illuminated, in particular, for small angles of incidence of the X-ray beam. Without the knife-edge, X-rays would be incident on a plurality of samples and the resulting scattering would significantly complicate signal analysis. The knife-edge is fixed in space and is aligned manually. The samples within the sample holder are moved in position in the x and y direction and measured individually. Reflectometry measurements are not possible using this apparatus, since the surface of individual samples may not be aligned with the surface of the surrounding sample holder or cannot be prepared to be flush with the surface of the sample holder. In the event that the surface of the sample is below the level of the sample holder, that surface is inaccessible to reflectometry measurements, since such measurements are typically made at angles within the range of 0 to 5 degrees relative to the horizontal. If the sample is excessively high, the angle of incidence is in error (see the brochure “XRD 2”, Bruker AXS GmbH, Karlsruhe, Germany, 2008).
Another device of prior art proposes an X-ray analysis system, which is suitable for large volume, rapid series, automated measurement processes. Wafers can be examined with spatial resolution and each particular measuring point can be adjusted and aligned with respect to the X-ray beam in a highly automated manner. When a plurality of small wafers are to be measured sequentially while disposed within a common support, problems result due to the fact that not all the wavers have the same thickness. Measurements can also be distorted by thin layers which are deposited on the wafer surfaces. An upstream wafer may cast a shadow on a downstream wafer, thereby preventing initial measurements at an angle of approximately zero degrees, cause falsification of the reflectometry measurements, and/or generate unreliable data (see the brochure “FABLINE”, Bruker AXS GmbH, Karlsruhe, Germany, 2008).
In view of these problems and difficulties regarding devices of prior art, it is the underlying purpose of the present invention to develop a system for X-ray reflectometry measurements on a plurality of samples which prevents signal cross-talk to neighboring samples or to the sample holder, while assuring an alignment which can be parallel to the incident beam.